Electric lamp



Feb. 25, 1941. V N HORN 2,232,816

ELECTRIC LAMP Filed Jan. 19, 1940 FIE. 1. H

20 I ll /9--" ii? I 7 F ii: 2/

v Inventor:

Irving H. VanHorn,

is Attorney.

, Patented Feb. 25, 1941 PATENT OFFIQCEY nmcrnro LAMP Irving B. VanHorn, East Cleveland, Ohio, as-

signor to General Electric Company, a corporation of New YcrhApplication as, 19, 1940, Serial No. 314,640 Claims. (01. 176-34) Myinvention relates in general to. electric incandescent lamps comprisinga sealed bulb containing a filament adapted to operate at a hightemperature. More particularly, my invention 5 relates to a heatprotective arrangement for such lamps.

In the operation of electric incandescent lamps of the high wattagetype, various P s of the lamp, such as the bulb wall, stem, and thebase,

to are heated to very high temperatures by the heat radiated by thefilament. This is particularly true in reflecting ineandescentlamps ofthe type in which the side wallportion of the bulb is formed as areflecting surface and the highlli wattage filament is mounted inrelatively close relation to that portion of the bulb wall adjacent ,thebulk neck, such a filament location being necessitated by opticalrequirements. When such lamps are burned in a base-up position, the neckand adjacent portions of the bulb wall are apt to be heated to such ahigh temperature as to cause a cracking of the glass. Furthermore, theexcessive heat in the neck portion of the bulb may prove to be injuriousto the lamp base and in some cases even to the lamp socket.

One object otmy invention is to provide an electric incandescent lampwith a heat protecting device for shielding the bulb neck and lamp basefrom the heat radiated by the lamp filament.

80 Another object of my invention is to provide Still another object ofmy invention is to provide a relatively high-wattage reflecting typeincandescent lamp employing a relatively small sized envelope.

A feature of the invention is the provision of a disc of insulatingmaterial in the neck ofrthe bulb between the lamp m and the filamenttogather with a wire screen element of cylindrical shape secured to theperiphery of the insulating disc and extending longitudinally of thebulb neck to a point a relatively slight distance below the filament. g

Further objects and advantages of my invention will appear from thefollowing detailed descriptlon' of a species thereof and from the accomp ny s drawing in which; I

Fig. 1 is an elevation, 'partlyin section, of an 60 electricincandescent lamp comprising my invention; and Fig. 2 is a perspectiveview or the lamp as to the invention comprises a hermetically sealedbulb It containing a gas filling such'cs nitrogen, argon 'or othersuitable gas, and having a neck portion H and a base l2 secured to saidneck portion. The base may be of the conventional screw-threaded or anyother suitable type. The bulb proper is formed with a flattened topporticn l3 having a curvature of relatively large radius and areflecting side wall portion l4 shaped to conform to a surface of anydesired optical reflecting'shape such as, for instance, a m

itinuing for a short distance along the said neck. The flattened topportion i3 is left clear for' the transmission of the light raystherethrough. The

inner surface of the bulb, including thegreater portion of the bulbneck, is preferably formed with a light frost. .As a result, the lightrays transmitted through the top portion it are somewhat diilused.

Mounted within the bulb it symmetrically about the focal point oroptical center of the refiecting suriace It is an electric energytranslation element or filament it or a refractory metal, preferablytungsten. This filament preferably comprises a coil formed into a i-shape with the plane of the V extending transversely of theiongitudinal axis 01' the bulb. The filament is of relativelyhighwattage such as, for instance, 300 watts or higher, and is supported atits ends by a pair oileading-in wires l1, l8 preferably of nickel. Theseleading-in wires are sealed in the pres portion 2b of an inwardlyextending stem l9 and are soldered or otherwise secured to the baseshell 2| and eyelet 22. The V-shaped filament is further. supported atits mid-point or 40 apex by a support wire 23 the lower end or which is.embedded in a button lot-med at the upper end of a glass arbor v25extending upwardly from the stempress 20. v Motmted within the neck llof the bulb be- 46 a substantially cylindrical metal shieldor wire 50screen member '21 disposed substantially concentrically within the bulbneck H. The disc 26 is preferably made of a ceramic materialcommerically known as Alsimag, but it may be made'ot any ceramicpossessing iairstrength'and 6t characterized by freedom frommoisture,such as centrically within the bulb neck just above the button 24 on theglass arbor 25, and is supported in such position by two support wires28, 29 and also by the filament support wire 23. The disc support wires28, 29 are embedded at one end in the glass button 24 and extendlaterally therefrom. At their outer ends, the said disc support wiresare bent around the edge or periphery of I the ceramic disc, as shown at30, so as to rigidly .clamp the same. The filament support wire 23 isformed with a laterally extending bent portion 3| (Fig. 2) whichlikewise clamps around the edge of the ceramic disc 26. The threesupports 23, 28 and 29 for the disc 26 are arranged approximately 120apart so'as to support the disc at equally spaced points around itsperiphery. To prevent rotation of the ,disc, the periphery thereof isprovided with notches 32 into which the support wires 23, 28 and 29extend. The disc 26 is further provided with a pair of openings 33, 33

through which the leading-in wires l1, l8 extend.

The cylindrical shield or wire screen member 21 surrounds the ceramicdisc 26 and extends from a point just below the filament l6 to a pointopposite the stem press or thereabouts. This screen member is secured,at a point intermediate its length, to 'the periphery of the ceramicdisc 26. For this purpose, the inner surface of they screen member 21 isformed with an annular groove 35 which receives the edge of the ceramicdisc'fit. The wire screen member is made of suitable material, such asnickel wire, and with suitably sized mesh openings, such as,for'instance, 20 per inch. The cylindrical screen member is formed froma fiat screen which is first provided with the groove The ceramic disc26 serves primarily as a heat deflector to shield the bulk neck I I,glass stem an,

the lamp base I2, and even the associated lamp socket, from the heatradiations of the filament when the lamp is burned in a base-upposition- Furthermore, the disc 26, being made of a ceramic materialwhite in appearance, also serves as a. light reflector to redirectforwardly into the beam all those rays from the filament which wouldotherwise pass out through the bulb neck and be lost. In this manner,undesirable back-light through the uncoated portion of the bulb neck upthe hot gas convection currents within the I bulb and efiectivelymaintains the neck and adjacent side wall portions 35 of the bulb atpermissible temperatures. Without the' wire screen member, the heat raysfrom the filament would be deflected by the ceramic disc 26 against thebulb neck II at points closely adjacent the periphery ofthe disc, thuscausing intense localized heating of the glass at such points. Such anintense localized heating would cause the reflecting coating IE to burnat suchpoints and so present an unsightly appearance, or it may resultin the cracking of the glass. Consequently, the wire screen member mustbe employed in conjunction with, and inaddition to, the ceramic disc 26in order to obtain eflective protection of both the bulb and thereflecting coating from the heat radiations.

small sized bulb for lamps of relatively high wattage.

To enable the cylindrical wire screen member 21 and the refractory disc26 to eifectively per- Because of such eil'ectlve protection,

it is therefore possible --to,employ a-relatively form their .heatprotective functions, they must be of adequate size in relation to thebulb neck and the lamp filament. The disc 26 should be made of adiameter approximating that of the bulb neck so that it extends acrosssubstantially the entire space within the bulb neck and substantiallycloses oil the same, but with its periphery slightly spaced from theinner surface of the'bulb neck. The cylindrical wire screen member 21should be of such a diameter'that, if extended, it would enclose thefilament l6 as well as the leading-in wires l1, l6 and support wire 23.In other words, the cylindrical screen member, mounted concentricallywithin the bulb neck, should be of such a diameter that the laterallocation of any given element of its surfacewill lie intermediate thecentrally mounted filament and the bulb neck wall. In addition, the wirescreen member 21 should be of sumcient length, i. e., should extend asufiicient distance towards the filament id to more or less shield fromthe filament the relatively sharp-curved joining portions 35 of the bulbjoining the bulb neck and side wall portions H and M, respectively. Suchreversely curved joining portions are of little assistance in theproduction of the resultant light beam so that the interposition of thewire screen between the filament and such relatively inefiectivejoining-portions 36 does not cause any appreciable loss in the intensityof the projected beam. With the particular arrangement shown in thedrawings, the wire screen member 2? and ceramic disc 26 togetherfunction as a heat protective device or shield not only when the lamp isburned in a vertical base-up position, but even when the lamp is tiltedto a position at an appreciable angle from vertical base-up position,such as or thereabouts. v

In addition to its function as a heat protecting device, the wirescreerr' member 21 also serves as an eifective blackening collector whenthe lamp is burned in a position approximating a base-up position. Thewire screen collects a considerable percentage of the filament particlesvaporized oi the filament during operation which might otherwise bedeposited on the-bulb wall. Thus, blackening of the bulb is materiallyreduced with consequent maintenance of lamp efiiciency for a longerperiod of time.

Although I prefer to employ a wire screen for the purpose of protectingthe bulb neck and adjacent portions of the bulb side wall from the heatradiated by the filament, other suitable means may be employed ifdesired. Thus a solid metal shield in the shape of a. cup may be mountedon the ceramic disc 26 so as to face the filament It. In such case, themetal cup is preferably made of a material having a surface which willreflect light so that the metal cup has the 7 additional function of alight reflector.

While such a'metal cup is effective .in preventing overheating andcracking of the glass bulb, it does not diflfuse the hot gases withinthe bulb or collect the blackening particles as efiectively as does thewire screen member 21.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An electric incandescent lamp comprising a sealed glass bulbcontaining a gas fllling and having a neck portion, an electric energytranslation element of relatively high wattage mount-' ed within saidbulb in relatively close relation to said neck portion and normallycausing overheating of said neck portion, and a heat protective devicemounted within said bulb to de- 'flect'and diffuse the hot gas currentstherein,

said device comprising a disc of refractory material mountedcentrally'within said neck portion and extending transversely thereof,said disc deflecting the hot gas currents away from said neck portion,and a cylindrical wire screen member disposed substantiallycencentrically within said bulb neck and extending between said disc andsaid translation element. said wire screen member being arranged todiffuse the hot gas currents within said neck portion and preventover-heating thereof.

2. A reflecting electric incandescent lamp comprising a sealed glassbulb containing a gas filling and having a side wall portion and a neckporthe hot gas currents away from said neck portion, and a cylindricalwire screen member disposed substantially concentrically within saidbulb neck and extending between said disc and said translation element,said wire screen member being arranged to diffuse the hot gas currentswithin said neck portion and prevent over-" heating oi the said neckportion and the reflecting coating thereon.

8. A reflecting electric incandescent lamp comprising a sealed glassbulb having a side wall portion and a neck portion, a continuousreflecting coating on the inner surface of said side wall and neckportions-an electric energy translation element of relatively highwattage mounted within said bulb in relatively close relation to saidneck portion and normally causing overheating of said neck and adjacentside wall portions, and a heat protective device mounted 7 within saidbulb to deflect and difluse the hot. gas currents therein, said devicecomprising a aesaerc i 3 'reflectingdisc of refractory material mountedcentrally within said neck portion and substantially closing ed thesame, and a cylindrical wire trically within said bulb neck andextending between said disc and said translation element. saidcylindrical wire screen member being oi approximately-the same diameteras said disc with its upper edge located a relatively slight distancebelow said translation element.

4. ;A reflecting electric incandescent lamp comprising a sealed glassbulb containing a gas filling and having a side wall portion and a neckportion, a continuous reflecting coating on the inner surface of saidside wall and neck portions, an electric energy translation element ofrelatively high wattage mounted within said bulb in rela tively closerelation to said neck portion and normally causing overheating of saidneck and adjacent side wall portions, and a heat protective devicemounted within said bulb to deflect and diffuse the hot gas currentstherein, said device I comprising a disc of refractory material mountedcentrally within said neck portion and extending transversely thereof,said disc deflecting the hot gas currents away from said neck portion,and a cylindrical wire screen member surrounding said disc and securedto the periphery thereof, said wire screen member extending from saiddisc towards said translation element, the upper edge of said wirescreen member being located a relatively slight distance below saidtranslation element. 4

5. A reflecting electric incandescent lamp comprising a sealed glassbulb containing a gas filling and having a side wall portion, a neckportion, and an inwardly projecting stem in said neck portion, acontinuous reflecting coating on the inner surface of said side 'walland neck portions, a glass arbor extending longitudinally of said bulbfrom the inner end of said stem, an electric energy translation elementof relatively high wattage mounted within said bulb in relatively closerelation to said neck portion and normally causing overheating of saidneck and adjacent side wall portions, and a heat protective devicemounted within said bulb to deflect and diffuse the hot gas currentstherein, said device comprising a reflecting disc of reiractorymaterialmounted centrally within said neck portion and substantially closing offthe same, said disc being supported by a plurality of support wiresembedded ln said glass arbor, and a cylindrical wire screen memberdisposed substantially concentrically within said bulb neck andextending between said disc and said translation element, saidcylindrical wire screen member being of approximately the samediameteras said disc and being secured to'the periphery thereof, the Uppr edge oi said wire screen member terminating a relatively slightdistance below said translation element.

IRVING- H. VAN HORN.

CERTIFICATE OF CORRECTION.

Patent No. 2,252,816. February 2 1911;.-

IRVING a. VAN 110m.

It is hereby certified that error appears inthe printed specification ofthe aboire nmdbered patent requiring correction'es follovia Page 5 firstcolumn, line 514., claim-5, after the herd 'bulb" insert "containing agas filling and-- and that the said Letters Pateilt should be read withthis correction therein that the same may conform to the record of thecase in the Patent Office. X

Signed and sealed this 25th day of March, A. b. -19L1.

-fien ry van Arsdale, Actitig Commissioner of Patents.

